Pumping means in refrigerating systems



Sept. 26, 1939. L. F. WHITNEY PUMPING MEANS IN REFRIGEHATING SYSTEMS Filed June 10, 1938 Jhveator; a721, W72

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i ||||||i||| i LY l I l l l ILII k Patented, Sept. 26, 1939 PATENT, OFFICE 2,114,303 PUMPING MEANS m narmenm'rnve srs'rnms Lyman Whitney. Cambridge, Mass assignor, by mesne assignments, to Stator Corporation, ,a corporation of Rhode Island Application June 10,1938, Serial No. 213,014

. 6 Claims.

This invention .relates to improved refrigerating systems and the like, andmore particularly to such systems provided with improved arrangements of pumping means including drop '5 tubs, ,for example. the present invention may be employed in a refrigerating system of the aspirator type which operates at low pressures and which is provided with a purger of the droptube type wherein successive liquid globules en- 10 train and compressbodies of non-condensable gas, the gas being exhausted to the atmosphere.

As disclosed in Comstock Patent No. 1,892,869, issued January 3, 1933, such a purger may be used to particular advantage with a system employing mercury as a propellant, the mercury passing in the form of separate globules through a drop tube wherein successive bodies of non- 'condensable gas are compressed. The lower end of the drop tube may be arranged in a mercurycontaining well, the upper surface of the mercury in the well being exposed to atmospheric 1 pressure. In a system of. this general type, the purger supply tube may ordinarily be connected to the refrigerant condenser and the. purger therefore may not onlypump non-condensable gases but may alsopump refrigerant vapor. Since-the vapor is .at a relatively low absolute pressure in the condenser, and since the purger has a relatively small capacity it may operate indeflnitely-without exhausting an objectionably large quantity of refrigerant from the system. My copending application, serial No. 157,402, filed October 5,1937 disclosed an arrangement of the purger supply tube. so that it may be kept at a relatively high temperature to preclude condensation of refrigerant therein, andthus to pre- 'clude the supplying of liquid refrigerant rather than, vaporous refrigerant to the purger.-

As fully disclosed in my copending application Serial No. 171,324,-flled October 27, 1934', in a system of the type employing mercury as a propellant and employing an aqueous'reirigerant there may be a tendency, under some conditions for the propellant and refrigerant to form a sludge which may become relatively thick and may resemble mud. Such a sludge is disadv'an tageous since it tends tp clog pipes of small dimeter and since it retains mercury in parts or the system where it is not desirable, thus tending m to necessitate the useof a larger amount of mercury in the system to assure satisfactory operation. I have found thatover a long period .of time such sludge n aydevelop in a purger of the type describedtfluch sludge-m ht possibly coi- 55 lect toa sumcient extent to clog the drop tube kept relatively warm.

creased pressure results 'in liqueiication of the refrigerant as it approaches the lower 'part of 10 the drop tube. v Since, however, an increased temperature of the refrigerant in this part of the tube will result in a .higher vapor pressure, the refrigerant does not liquefyas soon in passing down the tube if the purger is kept relatively l5 warm. Consequently the purger does not pump. as much refrigerant out of the system as would otherwise be the case. Furthermore, warming the purger for some reasonalso materially impedes even the slight formation of sludge which 20 might otherwise occur. I

The mercury which is supplied tothe purger is received from the aspirator assembly of the refrigerating system, and accordingly is quite warm, so that I have found that the temperature as of the purger may normally be kept sufliciently high, if the purger is suitably surrounded by heat-insulating material. This arrangement not only results in substantially preventing the formation of sludge in'this part of the system, but so 'it also results in a slight increase in operating eiiiciency, since the temperature of the mercury returning through the purger to the boiler of the system does notfall so low 'as otherwise would-be the case, and it is therefore not necessary to. heat this mercury so much as would otherwise be necessary in order to cause revaporization.

In the accompanying drawing: a Fig. 1 is a broken diagrammatic view of 'a refrigerating system in which the principles of the 40 present invention'are embodied;

Fig. 2 is a broken sectional view of the purger assembly;

Fig. 3 is anenlarged section on line i-d of Fig.- 1; and a Fig. 4 is an isometric detail of a portion of an insulating'casing. I

The principles of the present invention may be used to particular advantage with a refrigerating system of the aspirator type which employs 50 a propellant such as mercury, and an aqueous refrigerant. Such a system is diagrammatically shown in Fig. 1, and is'provided with a mercurycontaining boiler I having any suitable heating' means such as a burner 1. Mercury vapor from i v the nozzle 4 and the mixing chamber 5 may be located in a heat-insulating housing 1'. This housing may conveniently be formed of sheetmetal and may be filled with material.

Refrigerant vapor is drawn from the cooler 3i discrete insulating through a vapor duct 30 to the mixing chamber I of the aspirator assembly. The funnel 8 of the aspirator assembly preferably is disposed outside of the insulating housing 1 and may be.

provided with any suitable cooling means such as heat radiating fins 9. Refrigerant vapor may pass from the funnel 8 through a duct I 0 to a refrigerant condenser ii. The-duct I! preferably may have a portion juxtaposed to a warm part of the system, such as the funnel I, and if desired this duct may be provided with internal after. the manner taught in the copending application of William E. Whitney, Serial No. 171,301, filed October 27, 1937, to impede the for,- mation of sludge. Condensate from the condenser II is received by a drum I2 which is connected to a refrigerant return tube IS. The lower end of the latter may be connected to an'inclined duct l6.

Condensed mercury is received from the lower end of the funnel 8 by a drain 20 which is connected to a small chamber 2|. Adownwardly extending continuation it of the inclined pipe i6 is also connected to this small chamber, while an upwardly inclined duct- 23 extends from this chamber to the entraining chamben 24 of the purger 25. The connection between the duct 23 and the entraining chamber of the purger is a spill-over connection which determines the-approximate height of the mercury in the region of the Junction of tube It and inclined duct ii.

The upper end of the latter is connected to a duct 30 extending above the liquid level in the cooler Ii. The upper end of this duct is connected with a downwardly extending duct 33 which communicates with a large diametered duct 34 extending upwardly to the bottom of the cooler. The lower partof this duct is connected to a sludge separating drum IS. The upper part of the latter communicates through avapor duct 36 with the head of the cooler Ii. The lower part of drum I6 is connected to a dr Q! for receiving any Irnsergury which condenses in the mixing cham- A spill-over connection is provided between the duct 81 and a duct I! which extends downwardly to form one leg of a trap 40, the opposite leg of the latter being connected to .a propellant return duct 43 which communicates with the bottom of the boiler I.

.In a system of this character condensed refrigerant passes through the tube II to a trap at the junction of this tube and the inclined duct it, this trap being of the type more-fully disclosed in my copending application No. 171,324; and serving to balance the diii'erence between the cooler and condenser pressures. From this trap the refrigerant passes through the ducts 80 and 3I and rises through the upper part of the large diametered duct 84 to the cooler 3i. Mercury or sludge may pass from the cooler throug'hthe large diametered duct 34 and into the drum 3!. The preferred arrangement of this duct and drum is more fully disclosed in my copending application No. 207,268, med Ma fii, 1938. it any sludge in my copending riser is received by the drum, refrigerant vapor, is drawn'from this sludge through the tube 36, so

that the remaining mercury may coalesce in the normal manner. The spill-over connection between ducts 3-1 and 39 determines the normal mercury level in the drum 35.

A purger supply tube is connected to the upper partof the condenser drum i2 and to the entraining chamber 24 of the' purger. In order to impede the condensation of refrigerant vapor in the tube 50, a portion of the tube preferably may be disposed adjoining a hot part of the system such as the funnel 8, while the lower part of the tube may be disposed in" insulating housing 1. This purger is of the general type disclosed in my copending application Serial No. 167,402, and

-is provided with a' drop tube ii of small internal diameter which receives globules of mercury from the spill-over connection between chamber 2 3 and duct 23. Bodies of refrigerant vapor and non-condensable gas are normally entrained between the successive globules of mercury in the tube 5i, these bodies being compressed as they pass'downwardly to the lower part of the tube.

As a result of this increase in pressure, the refrigerant vapor may be liquefied by the time it reaches the lower part of the tube. The lower end of the tube is arranged in a mercury. containing well 54 which is'provided with a vent tube 55 opening into the atmosphere. It is thus evident that the surface of the mercury in well 54 is exposed to atmospheric pressure. A mercury duct 56 may be arranged concentrically about the drop tube 5i and may form a downwardly extending continuation of the. chamber 24. The

' flared upper end 5| of the drop tube 5| preferably may rest on a collar Hand may cooperate therewith to provide a very small pressure-equal izing opening between the chamber 24 and the v upper part of the mercury duct 56. The upper end of the boiler return duct 43 is connected to the mercury'duct Ii to receive mercury therefrom.

The lower end of the drop tube 5i preferably extendsbelow the open lower end of the mercury duct 56 and is provided with a. detachable deflector 58 of the type disclosed and claimed in the w. Tibbetts,

Serial No. 168,958, filed October 14, 1937.

In accordance with this invention, the purger copending application of Raymond assembly preferably is housed in an insulating casing. -For this'purpose I may employ an insulating casing 60 at the front of the insulating housing 1. As shown in Fig. 2, this insulating casing 50 may have one vertical wall provided by "a portion of the wall of housing I, while the remaining vertical walls thereof may be provided by a sheet metal member 6| which cooperates with the wall of easing I in affording a box-like enclosure for the purger. The casing 60 may be provided with a movable lower closure 5 (Fig. 4) and 'a removable upper closure 66. This casing is. filled with insulating material 62, which is preferably of the fibrous type. The purger is arranged so that the vent tube 55 extends outwardly through an opening in the wall ii. If

desired, a suitable receptacle may be arranged to catch mercury which would flow from this vent tube, if a large leak should develop in the system. so that the pressure within the system could rise to approach atmospheric pressure.

The upper part of the purger may be.provided with a detachable sealing device 1i such as shown application Serial No. 167,402,

while the lowerpart of well 54 may be provided with a detachable member 12. Consequently after removal of the closures 65 and 66, the sealcury is received by the purger from the funnel 8. Since the purger 25 is heat insulated, this mercury serves to keep the purger warm. As a result the condensation of refrigerant .vapor entrained in the drop tube 5l is'delayed until the refrigerant reaches a substantially lower level in the tube than would be the case were the tube uninsulated. I have found that this arrangement system.

resultsin a very substantial reduction'in the tendency toward sludge formation in the purger which otherwise might occur over a long period of time, and that it also results in the exhaustion of less refrigerant from the system..

In practice the pipe 20, the small chamber 2| and the pipe 23 preferably may be enclosed in insulating material to aid in keeping the mercury warm as'it passes to the purger.

I have found that substantial advantages may be realized even if the insulation is not provided for the full height of the purger, it being more important to insulate the upper part of the drop tube, for example the insulation may extend. downwardly only to the upper part of the well 54. Thus, for example, the upper part of the drop tube normally may' be kept at a temperature of at least F. and preferably well above F. I have also found that the advantage of the present invention can be realized to a much greater extent, if the purger supply tube is kept relatively warm as by juxtaposition to a but part of the It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. Refrigerating apparatus comprising'a propellant circuit and a refrigerant circuit having a part in common, wherein refrigerant vapor is pumped by entrainment in propellant vapor, a drop tube of restricted internal diameter, a duct for supplying liquid propellant from said part in common to said tube, a duct for supplying fluid for entrainment by propellant globules in the tube, and heat-insulating material surrounding said tube.

2. Refrigerating apparatus comprising a propellant circuit and a refrigerant circuit having a part in common wherein refrigerant vapor is pumped by entrainment in propellant vapor, said refrigerant circuit including arefrigerant condenser, a purger including a drop tube of restricted internal diameter, means for supplying propellant globules to the upper end of the drop tube, a purger supply tube to direct non-condensable gases from the condenser to the purger, and heat-insulating material surrounding the drop tube for a substantial portion of its height to retard condensation of refrigerant vapor entrained between propellant globules in said tube.

3. Refrigerating apparatus according to claim 2 wherein the means for supplying propellant globules to the upper end of the drop, tube is arranged so that said globules normally have a relatively high temperature thus to warm the purger.

4. Refrigerating apparatus according to claim '2 wherein the supply 'tube is juxtaposedto' a portion of the system having a relatively high temperature thereby to preclude condensation of the refrigerant in the tube.

5. Refrigerating apparatus comprising a propellant circuit and a refrigerant circuit having a part in common wherein refrigerant vapor is pumped by entrainment in propellant vapor, said refrigerant circuit including a refrigerant condenser, a. purger including a drop tube of restricted internal diameter, a well containing a body of propellant surrounding the lower part of the drop tube, means for supplying propellant globules to the upper end of the drop tube, a purger supply tube to direct non-condensable gases from the condenser to the purger, a heatinsulating housing surrounding the major portion of the drop tube and the upper part of the well, and a vent tube extending from the upper part of the well through the housing and providing a gas-exhausting vent outside of said housing.

6. Method of operating a refrigerating system of the low pressure aspirator type which includes a cooler, a condenser and a purger of the droptube type, comprising pumping refrigerant vapor from the cooler to the condenser by entrainment in a stream of propellant vapor, while maintaining a subatrnospheric pressure in the system by entraining gaseous bodies from the condenser between globules of liquid propellant in the drop tube, thereby compressing said bodies and liquefying refrigerant vapor included therein, exhausting the gases thus compressed to the atmosphere, and concomitantly maintaining the upper part of the drop tube at a temperature above 150 F. to

delay condensation of refrigerant in the tube thereby to impede sludge formation in the purger. LYMA N F. WHITNE 

